1. Field of the Invention
This invention relates to a manipulator for engaging a pouring tube with the discharge gate of a pouring ladle, which manipulator comprises a post and a boom, which is adjustably mounted on the post and is operable to force the pouring tube against the discharge gate and is pivotally movable about two axes, which are at right angles to each other.
2. Description of the prior Art
For a central of the flow of molten steel out of a pouring ladle into a succeeding distributor, a pouring tube is forced against the bottom outlet of the pouring ladle and is used to conduct the molten steel from the pouring ladle into the distributor. By means of a manipulator that pouring tube is engaged with a mating centering extension provided on the discharge gate of the pouring ladle and to open the discharge gate valve is moved in unison with that gate into alignment with the bottom outlet of the ladle. For that purpose the manipulator must be movable in unison with the discharge gate and with the pouring ladle while the required pressure is applied. From EP-A-0 160 593 it is known for that purpose to mount the pouring tube on a boom, which is movably mounted on a slide, which is displaceable along a past and operatively connected to a drive so that the pouring tube can be forced against the discharge gate under the required pressure by the drive via the slide regardless of movements of the boom which are transverse to the post. Such transverse movements can be performed by the boom because it is linked to the slide by means of a link, which is pivoted on a vertical axis. That known design has the disadvantage that the boom exerts a substantial torque on the slide so that the latter tends to be canted within its track. A canting of the slide in the associated track will adversely affect the transmission of force by the slide from the associated drive to the pouring tube and will prevent the application of a constant pressure for urging the pouring tube against the discharge gate.
Similar disadvantages are involved in another design, which is known from Austrian Patent Specification No. 360,188 and in which the post carrying the boom is mounted in a sleeve to be axially displaceable and rotatable relative thereto and is acted upon in an axial direction by a cylinder. In that case too, a torque is exerted on the post by the boom so that the post may be constrained in the associated bearing sleeve.
If the boom is pivoted on a horizontal axis, specifically on a vertical shaft that is mounted on the pouring ladle, so that the pouring tube can be adjusted in height, a transmission of torque from the boom to the vertical shaft can be avoided because the boom is pivotally movable. But in that case the boom can perform only an angular movement in a horizontal direction. This will be tolerable if the boom is mounted directly on the pouring ladle but will be intolerable if the boom is mounted on a manipulator, which is mounted separately of the pouring ladle.
From Austrian Patent Specification No. 364,103 it is also known that an additional degree of freedom can be provided for the movement of the pouring tube by means of a boom which is pivoted on a horizontal axis to a post that is rotatable about a vertical axis. This is accomplished in that the boom consists of two parts, which are hingedly connected on a vertical axis. But that design has also the disadvantage that the force by which the pouring tube is forced against the discharge gate causes the hinge between the two parts of the boom to be subjected to a torque about a transverse axis and that the provision of boom consisting of two hinged parts adds to the structural expenditure. Besides, the pouring tube can be adjusted only by hand.